This invention relates generally to locomotive motion and location determination, and more particularly to methods and apparatus for determining, to a high level of certainty, that a train has changed from one path to another.
Known systems for determining whether a turnout has been taken require a GPS (global positioning satellite) receiver to measure path curvature. As used herein, a path includes a track, or a road. The measured path curvature is correlated to a known curvature of a particular turnout to determine whether the turnout was taken. This determination is difficult to perform and is not very robust. It would therefore be desirable to provide robust methods and apparatus for determining whether a turnout has been taken.
There is therefore provided, in one embodiment, a path determination device configured to receive measured heading and distance information; determine heading corrections, distance corrections, and residuals utilizing at least one Kalman filter assuming a selected, known path was taken; and to determine a probability (prob) that the selected, known path actually was taken utilizing the determined residuals. The additional information utilized by the Kalman filters provides a more robust measurement indication of whether a particular path is taken than mere measurements and correlations of path curvature.